IActionResult vs ActionResult<T> in ASP.NET Core
|
|
IActionResult vs ActionResult<T> in ASP.NET Core
| Feature |
IActionResult |
ActionResult<T> |
| Type |
Interface |
Generic class inheriting from ActionResult |
| Flexibility |
Returns any IActionResult (e.g., Ok(), NotFound()) |
Can return both T and IActionResult |
| IntelliSense Support |
Limited for model type T |
Strong — compiler knows expected T |
| Use Case |
When returning multiple result types without fixed model |
When returning a model <T> and status codes together |
| Introduced In |
ASP.NET Core (since MVC days) |
ASP.NET Core 2.1+ |
Example: Using IActionResult
[HttpGet]
public IActionResult GetProduct(int id)
{
var product = _repo.Find(id);
if (product == null)
return NotFound();
return Ok(product);
}
Example: Using ActionResult<Product>
[HttpGet]
public ActionResult<Product> GetProduct(int id)
{
var product = _repo.Find(id);
if (product == null)
return NotFound();
return product; // Implicitly wrapped in Ok()
}
When to Use What
-
Use
IActionResultWhen : Full control over response types, no fixed model.
- You want full control over HTTP responses.
-
You're returning different types (e.g., FileResult, RedirectResult, etc.).
-
You’re not returning a model directly.
-
Use
ActionResult when:Cleaner syntax, better Swagger support, model + status code.
-
You want to return a model (
T) and still support status codes.
-
You want better Swagger/OpenAPI documentation.
-
You prefer cleaner syntax with implicit
Ok() wrapping.
Testing Tip
var result = controller.GetProduct(1);
var okResult = Assert.IsType<OkObjectResult>(result.Result);
var product = Assert.IsType<Product>(okResult.Value);